Z-MAP Satellite Launch Kit

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The Z-MAP Satellite Launch Kit and launcher on the launch pad
The second stage and satellite on an orbit around Kerbin

The Z-MAP Satellite Launch Kit (prior to 0.21 Z-MAP Satellite) is a stock rocket capable of bringing a small communication satellite into orbit. It consists of four stages with the last stage as the payload. The complete craft has a mass of 20.98 t with 78 parts, including two TT18-A Launch Stability Enhancers.

Craft Description

The Z-Map Satellite kit is a complete spacecraft capable of actually putting its payload into orbit!
Set includes: Payload satellite with booster stage, Liquid-fueled fin-stabilized launcher and two detachable boosters.
Return from orbit not guaranteed. Orbit also not guaranteed. Survival also not guaranteed. Keep out of reach of children and irresponsible adults.



The launcher has a very high thrust-to-weight ratio of 3.1 with all three engines running at 100% throttle. Because of the high acceleration the terminal velocity is exceeded very fast lowering the efficiency. Another staging order would use only the booster until they run out after 29 seconds and switching to the liquid fuel engine then, but the TWR will drop significantly. With the addition of tweakables in version 0.23, the thrust of the SRBs can be reduced before launch in the VAB, and doing so will increase the efficiency even more without changing the staging or turning off the middle LV-T45.

Usually it is possible to reach orbit with the boosters and the first stage. To avoid debris, the first stage should be shut off before reaching orbit, and the second stage should be used to achieve orbit. This stage has also its own Probodobodyne QBE command module, allowing it to deorbit itself after placing the payload in the targeted orbit. The launcher is also capable of bringing the satellite into a synchronous orbit around Kerbin and then deorbiting the second stage back to Kerbin.

The launcher itself appears to be loosely based off of the Augmented Satellite Launch Vehicle used by the ISRO.


The satellite in orbit.

The payload is a small 1.84 t heavy cubic communication satellite. It has four Communotron 16 on each corner of the front surface and one Communotron 88-88 placed directly on it. On each side except front and aft are six OX-STAT Photovoltaic Panels mounted. In the cube, on the other side of the Communotron 88-88, are the Probodobodyne OKTO2 command module, Oscar-B Fuel Tank and LV-1 Liquid Fuel Engine. To support the structure on each corner are four Cubic Octagonal Struts stacked on each other.

As there is a battery missing the only electronic storage are the 5 ⚡ in the command module, which isn't enough to operate the satellite in Kerbin's shadow.


2× Booster Stage 1 Stage 2 Stage 3 (Payload)
Engine RT-10 Solid Fuel Booster LV-T45 Liquid Fuel Engine LV-909 Liquid Fuel Engine LV-1 Liquid Fuel Engine
Diameter Small Small Small Small
Mass (t) 3.80 10.63 1.86 0.70
Burn time (s) 27.4 [Note 1] 125.6 [Note 1] 62.6 98.3
  1. 1.0 1.1 All engines of the booster and first stage ignite at the same time.


The stock Launch Kit and satellite have 5.45 km/s of delta-V -- enough to place the satellite in orbit around any planet or moon in the Kerbin, Eve, or Duna systems, or fly by Moho or Jool (but not quite Eeloo). This is marginally improved to 5.49 km/s by burning the solid rocket boosters on their own before igniting the LV-T45, but keeping the LV-T45 in the first stage allows the rocket to maintain a more consistent thrust-to-weight ratio and benefit from thrust vectoring throughout the launch, which may allow better efficiency in the atmosphere.

The satellite itself may be useful as a communication relay for science or control if CommNet (or a radio range mod such as RemoteTech) is being used. Without these, antennae are only useful for transmitting science, but there are no experiments on board.

The launcher can bring other payloads into a Kerbin orbit, like the Ion-Powered Space Probe. As the thrust-to-weight ratio is very high it is also possible to bring heavier payloads in a low orbit. If we take the launcher itself to be the TR-2V decoupler and everything below (easily done with the sub-assemblies feature added in version 0.22), the launcher can get 3.7 tons into orbit.